We propose to carry out research on the structure and function of biological membranes: 1) to investigate the molecular explanation for the low solubility of amphipathic molecules in real membranes which we have recently discovered; 2) to explore the proposal that the in vivo maturation of reticulocytes to mature erythrocytes involves the pinching-off of small regions of the reticulocyte membrane devoid of spectrin during circulation of the reticulocytes through the reticuloendothelial system; and 3) to explore the molecular mechanisms in cytotoxic T lymphocyte killing of virus-infected autologous and syngeneic target cells.